Low radial force vascular device and method of occlusion

ABSTRACT

An occlusion apparatus comprises inner and outer sheaths and an expandable flexible tubular sleeve. The occlusion apparatus is advanced to a target site in the blood vessel. A dilator having a soft, compressible tip may be advanced through a lumen of the inner sheath to facilitate the advancement of the occlusion apparatus. The sheaths are translated relative to one another to expand the flexible tubular sleeve to a funnel shape with a distal flush portion contacting the blood vessel inner wall and a proximal tapered portion. The proximal portion is fluid permeable so that blood can pass through to apply pressure on the vessel wall through the distal portion. A capture or traction device can be advanced out of the inner sheath lumen and retracted back therein to capture thrombus. The distal portion of the device may comprise an expandable mesh braid with a memory characteristic to limit expansion.

CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No.16/226,832, filed Dec. 20, 2018, now U.S. Pat. No. ______; which is acontinuation of U.S. application Ser. No. 14/554,348, filed on Nov. 26,2014; which claims the benefit of U.S. Provisional Application No.62/007,553, filed Jun. 4, 2014, which application is incorporated hereinby reference.

BACKGROUND

Occlusive vascular disease is a common ailment in people resulting inenormous costs to the health care system and this cost is growing as thepopulation ages. Many different endovascular devices have been developedto treat various segments and various conditions of this huge market.While many of these devices are quite effective at treating plaque,blood clots, occlusions, narrowing and the like, frequently they damagethe blood vessel wall which incites an exuberant reparative effort bythe body which results in a process termed restenosis. Restenosis is asecondary narrowing of the blood vessels caused by the injury to theblood vessel caused by the primary treatment.

Hence, there is a need for devices that successfully treat differentconditions of the blood vessels but do not damage the vessel wall andincite the exuberant healing response that may result in restenosis, orsecondary narrowing.

In some instances, it is necessary to temporarily occlude the bloodvessel to deliver medicaments, to retrieve blood clot, to provideembolic protection, to anchor the catheter system, and the like. Ballooncatheters are used frequently for these applications, but the outwardradial force of the apparatus sufficient to produce occlusion may alsobe sufficient to damage the vessel wall enough to cause restenosis. Asafe expansion of the balloon may be insufficient to arrest blood flowand blood may leak by the occluding member, which may propelmedicaments, debris, and blood clot downstream to block smallerarteries. Too much radial force may damage the vessel wall enough tocause the restenosis cascade phenomenon, which is initiated by injuryand damage to the smooth muscle cells in the media of the arterial wall,a well-known complication of balloon inflations. This cascade of eventsresulting in restenosis has been the “Achilles Heel” of vascularintervention as many interventions which distend the vessel, includingangioplasty, stent placement, and balloon occlusion, damage the vesselwall as they attempt to correct a blockage, remove a clot, or the like.Generally, this complication should be avoided at all costs.

Balloons are notorious for causing damage to the vessel wall as theyapply outward radial pressure that distends the blood vessel, injuringand damaging the blood vessel. The body's reparative effort comprises acomplex series of events that results in exuberant scar tissue weeks tomonths later which cause the vessel to narrow significantly, a processknown as “re-stenosis.”

Hence, it is an object of the present disclosure to improve upon thecurrent devices and provide blood flow occlusion in all predictablescenarios without causing damage to the blood vessel while doing so. Tothis end, devices and device features meeting at least some of theseobjectives discussed subsequently.

Additionally, improvements to other devices which may be utilized withoccluding catheters as part of a system for thrombectomy, anchoring,embolic protection, vessel occlusion, drug delivery and otherapplications will be described.

SUMMARY

The present disclosure relates to medical systems, devices, and methods.More specifically, the present disclosure relates to systems, devices,and methods to treat diseased or stenosed blood vessels.

Devices, systems, and methods are disclosed for occluding a blood vesseland/or capturing a blood clot or thrombus within. An occlusion apparatusmay comprise inner and outer sheaths and an expandable flexible tubularsleeve. The occlusion apparatus may be advanced to a target site in theblood vessel. A dilator having a soft, compressible tip may be advancedthrough a lumen of the inner sheath to facilitate the advancement of theocclusion apparatus. The sheaths may be translated relative to oneanother to expand the flexible tubular sleeve to a funnel shape with adistal flush portion contacting the blood vessel inner wall and aproximal tapered portion. The proximal portion may be fluid permeable sothat blood can pass through to apply pressure on the vessel wall throughthe distal portion. A capture device and/or a traction device can beadvanced out of the inner sheath lumen and retracted back therein tocapture thrombus. The distal portion of the device may comprise anexpandable mesh braid with a memory characteristic to limit expansion.

Aspects of the present disclosure may also be directed to a funnelcatheter comprising an outer tube, an inner tube slidably located withinthe outer tube, and a tubular sleeve having first and second ends andmovable between a radially expanded, use state and a radiallycontracted, deployment state. The first end of the sleeve may be securedto a distal end of the outer tube. The second end of the sleeve may besecured to a distal end of the inner tube. The sleeve may have amovable, generally U-shaped direction-reversing region so that when thefirst and second ends move relative to one another, the position of thedirection-reversing region may move relative to the distal ends of theinner and outer tubes. The direction-reversing region may comprise thedistal funnel catheter end. The sleeve may be comprised of anelastomeric coating applied or covering a part of the sleeve and a partof the sleeve which may not have an elastomeric covering.

Aspects of the present disclosure may also be directed to a method fordeploying a material-directing element within a tubular structure withina patient. A funnel catheter, having a distal funnel catheter end, maybe selected. The funnel catheter may comprise an outer tube, an innertube slidably located within the outer tube, and a tubular sleeve havingfirst and second ends and movable between a radially expanded, use stateand a radially contracted, deployment state. The first end of the sleevemay be secured to a distal end of the outer tube. The second end of thesleeve may be secured to a distal end of the inner tube. The sleeve mayhave a movable, generally U-shaped direction-reversing region, which maycomprise the distal funnel catheter end. The funnel catheter may bedeployed with the sleeve in the reduced diameter, deployment state andwith the sleeve being generally parallel to the outer and inner tubes.The direction-reversing region may be positioned at a chosen positionwithin a tubular structure within a patient. The distal ends of theinner and outer tubes may be moved relative to one another to cause: theposition of the direction-reversing region to move relative to the firstand second ends, the sleeve to form a distally-openingmaterial-directing funnel, and the distal funnel portion to contact theinner wall of the tubular structure. The funnel may have a distal funnelportion and a proximal funnel portion. The distal funnel portion maycomprise an elastomeric covering and the proximal portion may not becomprised of an elastomeric coating.

Aspects of the present disclosure may also be directed to an improvedtraction device which may be placed coaxially through the funnelcatheters described herein. The improved traction device may comprise anouter sleeve and inner member placed coaxially within the outer sleeve.Both the sleeve and the inner member may have proximal and distal ends.The distal end of the outer sleeve may be attached to the proximal endof a length of a deformable tubular braid. The distal end of the innermember may be attached to the distal end of the length of the deformabletubular braid. When the inner member is moved proximally relative to theouter sleeve, the deformable tubular braid may contract so that the endsof the deformable tubular braid are positioned closer together and thewaist of the tubular braid expands. The traction device can includefurther features described herein that are directed to the ease of useand more efficient function amongst other improvements. Prior tractiondevices are described in U.S. Pat. Nos. 6,238,412 and 6,699,260, issuedto the current inventor as a co-inventor.

Aspects of the present disclosure may also be directed to occlusionapparatuses for occluding a bodily vessel. An occlusion apparatus maycomprise an outer sheath, an inner sheath, and a flexible tubular sleevehaving a contracted configuration and an expanded configuration. Theouter sheath and the inner sheath may be translatable relative to oneanother to actuate the flexible tubular sleeve between the contractedand expanded configurations. The flexible tubular sleeve in the expandedconfiguration may have a funnel shape with a distal flush portionadapted to contact an inner wall of the bodily vessel when the flexibletubular sleeve is expanded therein and a proximal tapered portion. Atleast a part of the proximal tapered portion may be fluid permeable suchthat bodily fluid within the bodily vessel can pass through the fluidpermeable part to apply pressure on the inner wall of the bodily vesselthrough the distal flush portion. The bodily vessel will typicallycomprise a blood vessel and the bodily fluid within the bodily vesselwill typically be blood. The occlusion apparatus, however, may also beused with other bodily vessels such as bile ducts, esophagus, fallopiantubes, urethra, and intestines.

The inner sheath may be disposed at least partially within the outersheath. The flexible tubular sleeve may have a first end and a secondend. The first end may be coupled to a distal end of inner sheath and/orthe second end may be coupled to a distal end of the outer sheath. Thedistal end of the inner sleeve may be distal of the distal end of theouter sleeve when the flexible tubular sleeve is in the contractedconfiguration. The flexible tubular sleeve may be biased to assume theexpanded configuration with the funnel shape. For example, the flexibletubular sleeve comprises a shape memory material such as Nitinol. Theshape memory material may be fashioned in a way to be biased to assumethe funnel shape as described below.

At least a part of the distal flush portion may be fluid impermeable.The fluid impermeable part of the distal flush portion may be distal ofthe fluid permeable part of the proximal tapered portion when theflexible tubular sleeve is in the expanded configuration. The fluidimpermeable part of the distal flush portion and/the fluid permeablepart of the proximal tapered portion may extend over at least a fullcircumference of the flexible tubular sleeve. The fluid impermeable partof the distal flush portion may comprise an elastomeric covering.

The flexible tubular sleeve may comprise a mesh braid. The flexibletubular sleeve may comprise a U-shaped direction-reversing regionadapted to move relative to one or more of the inner and outer sheathsas the inner and outer sheaths are translated relative to one another.The U-shaped direction-reversing region may be disposed at a distal endof the flexible tubular sleeve. The distal flush portion of the flexibletubular sleeve in the expanded configuration may be adapted to apply aradially outward force sufficient to occlude fluid flow in the bodilyvessel.

Aspects of the present disclosure may also be directed to systems fortreating a disease within a bodily vessel. A system may comprise any ofthe occlusion apparatuses described herein. The system may furthercomprise a dilator advancable at least partially through a lumen of theinner sheath of the occlusion apparatus so that a distal tip of thedilator is distal of the occlusion apparatus. The dilator may have amalleable and oversized distal tip with a greater cross-sectional areathan a distal tip of the inner sheath of the occlusion apparatus.Alternatively or in combination, the system may further comprise atraction apparatus translatable at least partially through the lumen ofthe inner sheath so that an expandable mesh braid on a distal portion ofthe traction apparatus can be positioned and expanded distal of theocclusion apparatus.

The dilator and/or traction apparatus may have a guidewire lumen.Retraction of one or more of the dilator and/or traction apparatus whenadvanced distally past the occlusion apparatus can capture and retractmaterial in the bodily vessel into the lumen of the inner sheath. Theexpandable mesh braid of the traction apparatus may be configured toapply a predetermined limited amount of radially outward force whenexpanded in the bodily vessel and elongate to minimize distending ordamaging the bodily vessel as the expandable mesh braid is expanded. Thebodily vessel will typically comprise a blood vessel and the bodilyfluid within the bodily vessel will typically be blood. The occlusionapparatus, however, may also be used with other bodily vessels such asbile ducts, esophagus, fallopian tubes, urethra, and intestines.

Aspects of the present disclosure may also be directed to methods oftreating a bodily vessel. A method may comprise the steps of advancingan occlusion apparatus to a target site in a bodily vessel and expandinga flexible tubular sleeve of the occlusion apparatus to a funnel shapedexpanded configuration occluding the bodily vessel at the target site. Adistal flush portion of the flexible tubular sleeve may contact an innerwall of the bodily vessel when expanded. A proximal tapered portion ofthe flexible tubular sleeve may allow bodily fluid within the bodilyvessel to pass at least partially therethrough to apply pressure on theinner wall of the bodily vessel through the distal flush portion.

At least a part of the distal flush portion may be fluid impermeable andat least a part of the proximal tapered portion may be fluid permeable.To expand the flexible tubular sleeve, an inner sheath and an outersheath of the occlusion apparatus may be translated relative to oneanother. Such translation can move a U-shaped direction reversing regionof the flexible tubular sleeve relative to one or more of the inner orouter sheaths. The distal flush portion of the flexible tubular sleevein the expanded configuration may be adapted to apply a radially outwardforce sufficient to occlude fluid flow in the bodily vessel. Thisradially outward force may be from a combination of the inherentstructure of the expanded flexible tubular sleeve and the pressure fromthe bodily fluid passed through the proximal tapered portion. Theflexible tubular sleeve may be biased to assume the funnel shapedexpanded configuration. Expanding the flexible tubular sleeve maycomprise allowing the flexible tubular sleeve to assume the funnelshaped expanded configuration.

The occlusion apparatus may be advanced over a guide wire. The methodmay further comprise advancing a dilator through the occlusionapparatus. The dilator may be advanced through a distal end of theocclusion apparatus. The dilator may further be retracted within thebodily vessel to capture and retract material in the bodily vessel intoan inner lumen of the occlusion apparatus. The material captured andretracted may comprise a clot or a thrombus. The dilator may have amalleable and oversized distal tip having a greater cross-sectional areathan a distal tip of the inner sheath of the occlusion apparatus.

The method may further comprise a step of advancing a traction apparatusthrough the occlusion apparatus. The traction apparatus may have anexpandable mesh braid on a distal portion thereof. The tractionapparatus may be advanced through a distal end of the occlusionapparatus. The method may further comprise a step of expanding theexpandable mesh braid to appose the inner wall of the bodily vessel. Theexpanded expandable mesh braid may be configured to apply a limitedradially outward force when expanded in the bodily vessel and elongateto minimize distending or damaging the bodily vessel as the tubularouter sleeve is expanded. The expandable mesh braid may comprise aplurality of wires configured to exert a maximum predetermined outwardradial force when the expandable mesh braid is in the expandedconfiguration. The method may further comprise a step of retracting theexpanded expandable mesh braid within the bodily vessel to capture andretract material in the bodily vessel into an inner lumen of theocclusion apparatus. The material captured and retracted may comprise aclot or a thrombus.

Expanding the flexible tubular sleeve of the occlusion apparatus to thefunnel shaped expanded configuration may apply a radially outward forcefrom the expanded flexible tubular sleeve to hold the flexible tubularsleeve in place in the bodily vessel. The radially outward force maycomprise blood pressure transmitted through the expanded flexibletubular sleeve and an inherent radially outward force from the expandedflexible tubular sleeve. The radially outward force mostly may comprisethe blood pressure transmitted through the expanded flexible tubularsleeve. The radially outward force may be transmitted from blood passingthrough at least a portion of the flexible tubular sleeve.

Aspects of the present disclosure may also be directed to devices fordilating a bodily vessel. The device may comprise a shaft and amalleable and oversized distal tip coupled to the shaft. The shaft mayhave an inner lumen for the passage of a guidewire and may beadvanceable through a catheter lumen. The malleable and oversized distaltip may be coupled to the shaft and may have a cross-sectional areagreater than that of the shaft. The oversized distal tip may becompressible to be advancable through the catheter lumen. The malleableand oversized distal tip may comprise a first material and the shaft maycomprise a second material, the first material having a softer durometerthan the second material. The malleable and oversized distal tip mayhave a radial cut-out to provide compressibility. Typically, the bodilyvessel will be a blood vessel but the dilator devices may be used forother bodily vessels as well.

Aspects of the present disclosure may also be directed to methods fordilating a bodily vessel. The method may comprise the steps ofpositioning a dilator within a lumen of a catheter such that anoversized distal tip of the dilator is advanced out of the catheterlumen and decompresses and advancing the oversized distal tip of thedilator and the catheter to a target site. Typically, the bodily vesselwill be a blood vessel but the dilator devices may be used for otherbodily vessels as well. The target object will typically comprise ablood clot or a thrombus. The catheter may comprise an occlusioncatheter, and may further comprise expanding the occlusion catheter atthe target site to occlude the target site. The method may furthercomprise a step of retracting the oversized distal tip of the dilator tocapture a target object at the target site at least partially within anexpanded tubular sleeve of the occlusion catheter and/or the lumen ofthe catheter. The oversized distal tip of the dilator may have a greatercross-sectional area than that of a shaft of the dilator the oversizeddistal tip is coupled to.

Aspects of the present disclosure may also be directed to tractionapparatuses for treating a bodily vessel. A, traction apparatus maycomprise an inner shaft having a distal end, a tubular outer sleevecoaxially disposed over the inner shaft and having a distal end, and anexpandable mesh braid coaxially disposed over the inner shaft andcoupled to the distal ends of the inner shaft and the tubular outersleeve. The inner shaft and the tubular outer sleeve may be translatablerelative to one another to shift the expandable mesh braid betweencontracted and expanded configurations. The expandable mesh braid may beconfigured to apply a predetermined maximum amount of radially outwardforce when expanded in the bodily vessel and to elongate to minimizedistending or damaging the bodily vessel as the tubular outer sleeve isexpanded.

The mesh braid may comprise a plurality of wires. The plurality of wiresmay have been treated to provide a combination of stiffness andflexibility so that the expandable mesh braid applies the predeterminedmaximum amount of radially outward force when expanded in the bodilyvessel and elongates to minimize distending or damaging the bodilyvessel as the tubular outer sleeve is expanded. The plurality of wiresmay comprise a plurality of Nitinol wires. The plurality of wires mayhave been heat treated. The plurality of wires may be configured toexert the predetermined maximum amount of radially outward force whenthe expandable mesh braid is in the expanded configuration. Theplurality of wires may be configured to exert the predetermined maximumamount of radially outward force independently of the inner diameter ofthe bodily vessel.

The expandable mesh braid in the expanded configuration may beconfigured to expand to appose an inner wall of the bodily vessel whileminimizing resultant expansion of the bodily vessel. The expandable meshbraid may be expandable to a maximum predetermined outer diameter toapply the predetermined maximum amount of radially outward force. Theexpandable mesh braid may have a shape memory characteristic to limitexpansion of the expandable mesh braid to the maximum predeterminedouter diameter. Further translation of the inner shaft and the tubularouter sleeve relative to one another after the expandable mesh braid hasbeen expanded to the maximum predetermined outer diameter may axiallylengthen an outer surface of the expandable mesh braid. That is, adegree of translation of the inner shaft and the tubular outer sleeverelative to one another may have a non-linear relationship(s) with anouter diameter of the expandable mesh braid and/or a radially outwardpressure exerted by the expandable mesh braid. The expandable mesh braidmay have a permeable portion to allow fluid within the bodily vessel toenter an interior of the expandable mesh braid and may apply radiallyoutward pressure on the bodily vessel through an impermeable portion ofthe expandable mesh braid. Typically, the bodily vessel comprises ablood vessel.

Aspects of the present disclosure may also be directed to methods oftreating a bodily vessel. A catheter may be introduced to a target sitein the bodily vessel. A traction apparatus from within an inner lumen ofthe catheter may be advanced to position an expandable mesh braid of thetraction apparatus. The expandable mesh braid may be expanded within thetarget site. The expanded mesh braid may be retracted to capture andretract material in the target site into the inner lumen of thecatheter. The bodily vessel will typically comprise a blood vessel. Thecaptured and retracted material may comprise a blood clot or a thrombus.

To expand the expandable mesh braid, an outer surface of the expandablemesh braid may be apposed against an inner wall of the bodily vessel.The expandable mesh braid may be configured to apply a predeterminedmaximum amount of radially outward force when expanded in the bodilyvessel and to elongate to minimize distending or damaging the bodilyvessel as the tubular outer sleeve is expanded. The expandable meshbraid may comprise a plurality of wires configured to exert thepredetermined maximum amount of radially outward force when theexpandable mesh braid is in the expanded configuration. The plurality ofwires may be configured to exert the predetermined maximum amount ofradially outward force independently of the inner diameter of the bodilyvessel. The expandable mesh braid in the expanded configuration may beconfigured to expand to appose an inner wall of the bodily vessel whileminimizing resultant expansion of the bodily vessel.

The expandable mesh braid may be expanded to a maximum predeterminedouter diameter. The expandable mesh braid may have a shape memorycharacteristic to limit expansion of the expandable mesh braid to themaximum predetermined outer diameter. To expand the expandable meshbraid, an inner shaft and a tubular outer sleeve of the tractionapparatus may be translated relative to one another. Further translationof the inner shaft and the tubular outer sleeve relative to one anotherafter the expandable mesh braid has been expanded to the maximumpredetermined outer diameter may axially lengthen an outer surface ofthe expandable mesh braid. That is, a degree of translation of the innershaft and the tubular outer sleeve relative to one another may have anon-linear relationship(s) with an outer diameter of the expandable meshbraid and/or a radially outward pressure exerted by the expandable meshbraid.

To expand the expandable mesh braid, fluid within the bodily vessel maybe allowed to enter an interior of the expandable mesh braid and applyradially outward pressure on the bodily vessel through the expandablemesh braid.

INCORPORATION BY REFERENCE

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the present disclosure are set forth withparticularity in the appended claims. A better understanding of thefeatures and advantages of the present disclosure will be obtained byreference to the following detailed description that sets forthillustrative embodiments, in which the principles of the presentdisclosure are utilized, and the accompanying drawings of which:

FIG. 1 illustrates a side view of a prior funnel catheter with itsfunnel element contracted;

FIG. 2 illustrates a side view of the prior funnel catheter of FIG. 1with its funnel element expanded;

FIG. 3 illustrates a side view of an occlusion or funnel catheter withits funnel or braid element contracted and with a distinct portion ofthe funnel or braid element not covered by a membrane, according to someembodiments;

FIG. 4 illustrates a side view of the occlusion or funnel catheter ofFIG. 3 with its funnel or braid element in its expanded, funnel shapedconfiguration with a distinct portion of the funnel or braid elementcovered by a membrane and a distinct portion not covered by a membrane;

FIG. 5 illustrates a side view of a dilator usable with an occlusiondevice, in accordance with some embodiments;

FIG. 6 illustrates a cross sectional view of the dilator of FIG. 5 at aposition A in FIG. 5;

FIG. 7 illustrates a cross sectional view of the dilator of FIG. 5 atthe position A in FIG. 5, the dilator having an additional cutout;

FIG. 8 illustrates a side view of the dilator of FIG. 5 inserted intothe funnel catheter of FIGS. 3 and 4 in the contracted configuration;

FIG. 9 illustrates a side view of the dilator of FIG. 5 inserted intothe funnel catheter of FIGS. 3 and 4 in the expanded configuration;

FIG. 10 shows a graph of compressive unloading for the experimentalocclusion or funnel catheter of FIGS. 3 and 4, according to someembodiments;

FIG. 11 shows a side view of a prior traction device in its contracted,delivery configuration;

FIG. 12 show a side view of the traction device of FIG. 11 in itsexpanded configuration;

FIG. 13 shows a side view of the traction device of FIG. 11 expanded ina blood vessel;

FIG. 14 shows a side view of a traction device expanded in a bloodvessel, according to some embodiments;

FIG. 15 shows a graph of compressive unloading for a traction deviceaccording to many embodiments; and

FIG. 16 shows a side view of another traction device expanded in a bloodvessel, according to some embodiments.

DETAILED DESCRIPTION

There is a continuing need for improved medical devices and methods tomeet some or all the following objectives.

An objective may be to reduce cost. Cost reduction may be particularlyimportant in recent years where it is clear for safety and sanitaryreasons that many devices used in the vasculature should be single usedevices. Devices, even if performing a function in some improved manner,will not be widely used if they are considerably more costly than thealternatives available.

Another objective may be ease of use and simplicity of understanding.Ease of use and simplicity can encourage device adoption and use bymedical personnel. They can also tend to keep cost low.

Another objective may be to provide devices that entail procedures withwhich the medical profession is already familiar. By doing so, theskills that have been learned from previous experience can continue tohave applicability.

Another objective relates to the effectiveness and thoroughness withwhich the device performs, such as blockage removal and vesselocclusion. For example, it is generally important that a maximum amountof the blockage be removed, recognizing that no device is likely toprovide one hundred percent removal.

Another objective concerns safety—a matter, which is often so criticalas to trump the other considerations. It is generally important to avoidtissue trauma. In many circumstances, it is critically important to, forexample, avoid breaking up a blockage in a fashion that leads toflushing elements of the blockage throughout the body such as bydamaging the blood vessels by applying excess pressure on the vesselwall in an attempt to fully occlude the vessel so that blockages can beremoved and debris can be prevented from flushing downstream. A goal ofthe devices disclosed herein is to do just that: provide effectiveocclusion of a blood vessel to remove blockages and prevent debris fromflushing downstream in a manner which does not damage the vessel wall indoing so.

There are often trade-offs in design considerations to achieve the aboveinterrelated objectives. Extreme simplicity and a very simple proceduremight over compromise safety. Addressing all of these considerationsoften calls for some trade-off between the objectives while maintainingthe effectiveness and doing so safely.

FIG. 1 is an illustration of a prior art occlusion device or funnelcatheter 100 in which the proximal end 202 of the tubular mesh braid 200is attached to the distal aspect of the outer sleeve 194 and the distalend 204 of the tubular mesh braid 200 is attached to the distal aspect198 of the inner sleeve 196. In the contracted or non-deployedconfiguration, as illustrated in FIG. 1, the tubular mesh braid 200covers the distal aspect 196 of the inner sleeve 196. The catheter 100is essentially in a typical configuration of a standard catheter, albeitwith an outer sleeve 194 and inner sleeve 196 comprising the catheterwall. An impervious coating 216 covers the tubular mesh braid 200, butthere may be areas of various porosity 214 in which there is no membranewhich serves to enhance the expansile characteristics of the braid 200by providing areas that are not restricted from expanding because of theelastomer.

FIG. 2 is an illustration of a prior art device 100 placed into a bloodvessel BV and with the inner sleeve 196 withdrawn. Withdrawal of theinner sleeve 196 may cause the flexible tubular mesh braid 200 to bucklein a predetermined manner because of the manner in which the tubularmesh braid 200 was formed so that the tubular mesh braid 200 creates afunnel shape on the distal catheter. The margins of the funnel tipexpand to contact the blood vessel wall 210 with a predetermined amountof radial force to occlude blood flow. The length 212 of the wallcontact of the margin of the tubular mesh braid 200 may also beimportant in assisting the occlusion of blood flow. As well, the tubularmesh braid 200 may comprise a coating or a membrane 216 that isessentially impervious to blood but may comprise a variable porosityregion 215 in a portion of the braid. This variable porosity region 215can allow some fluid communication to the space between the inner andouter portions of the tubular mesh braid 200 when the tubular mesh braidis deployed in a funnel shape and can assist in the expansion of thetubular braid as there is less elastomer on the braid, hence lessrestriction to expansion. The variable porosity may also prevent avacuum from forming within the folded more or less impervious braid thatmay prevent it from expanding correctly into a funnel shape.

However, in cases with an exaggerated systolic blood pressure of 160 mmHg or in a larger vessel with exaggerated flow such as the carotid orrenal arteries, the outward radial force and the length of braidcontacting the vessel wall may not be sufficient to arrest the bloodflow on a consistent basis. By providing an outward radial forceadequate to arrest blood flow, the outward radial force may causecompression of the vessel wall 210, damaging the wall 210 similar to theforces exerted by balloon inflation which is known to damage the walland result in restenosis. Hence, there may be a need for improvedocclusion devices which do arrest blood flow in cases of exaggeratedsystolic blood pressure or exaggerated high flow states on a consistentand reliable basis, but without exerting an undue or exaggerated amountof force on the vessel wall to do so.

Moreover, there may be a dilemma with utilizing an outward radial forceas the primary means of arresting blood flow as the optimal radial forceto arrest blood flow varies as the optimal amount or size of theexpanded funnel tip to arrest flow may vary in different sized vessels.The radial force and the size of the funnel tip will be different in a 2mm coronary artery than in a 6 mm carotid artery and even stilldifferent in a 9 mm iliac artery. Hence, for different sized vessels,arresting the flow may demand the use of funnel tips with differentsizes and different radial forces and different length of the wallcontacting surface of the tubular mesh braid 200. This need fordifferent sizes may create a situation in which it may be difficult toarrest flow over a continuum of sizes and flow situations, which canoccur within a single vascular distribution as is the case in the lowerextremity, with one design and one size of funnel tip. With the priorart occlusion device 100, while the funnel tip may oppose and contactthe wall over a spectrum of sizes, the ability to occlude over thisspectrum of sizes may be limited and may necessitate funnel tips sizedspecifically for the vessel size. The radial pressure exerted on a 2 mmdiameter vessel will be greater than the radial pressure exerted on a 6or 9 mm diameter vessel. As well, because of the different bloodpressures in different patients and different flow rates in differentarteries within the same patient, devices should be constructed toprovide a greater force than is typically needed so to address the worstpossible case which is elevated blood pressure and flow although mostcases would not demand it. Hence, there may be a need for improvedocclusion devices which do arrest blood flow over a range of vesselsizes with an optimized funnel tip which provides radial forcesufficient to contact the wall but insufficient radial force to damagethe wall. Meeting these needs can be accomplished by adding one or morefeatures to the prior art occlusion device to improve upon it so thatthe occlusion device will arrest flow in cases of exaggerated systolicblood pressure, exaggerated high flow, and over a range of differentsized arteries.

The sealing or occlusion efficiency of the prior art device can besummarized by the formula:

Occlusion efficiency of prior art occlusion device=radial force ofbraid*length or area of contact.

Hence, the longer the length (greater area of contact), the less radialforce may be needed to occlude.

FIG. 3 is an illustration of an occlusion device or funnel catheter 100a in accordance with embodiments of the present disclosure in anundeployed or contracted configuration. FIG. 4 is an illustration of thesame occlusion device 100 a in a deployed or expanded configuration inthe blood vessel BV. The occlusion device 100 a can solve the problem ofthe prior art occlusion device 100 and can arrest blood flow completelyirrespective of the systolic blood pressure or the amount of flow withinthe vessel. The occlusion device 100 a may comprise a catheter with aninner sleeve 196, an outer sleeve 194, and a length of tubular meshbraid 200 in which the proximal end 202 of the tubular mesh braid 200 isattached to the distal aspect of the outer sleeve 194 and the distal end204 of the tubular mesh braid 200 is attached to the distal aspect ofthe inner sleeve 196. As with the prior art occlusion device 100, theocclusion device 100 a may be constructed so that the funnel tipcontacts the vessel wall location 212 with a radial or outward force andwith a length of contact with the vessel wall location 212 sufficient toarrest blood flow in most instances.

In addition to the two features present in the prior art device 100 toocclude flow, the current occlusion device 100 a also comprises adistinct coating or membrane free portion 215 of the tubular mesh braid200 in addition to the coated or membrane containing section 216. Fluidor blood may flow freely though this coating free or membrane freesection 215 of the tubular mesh braid, as indicated by the arrows 217,and by doing so will enhance the expansion of the wall contactingsegment 212 of the tubular mesh braid 217 by adding the transmittedblood pressure to the outward or radial force of the funnel tip asdemonstrated by the arrows 218 so that a seal is achieved no matter thesystolic blood pressure, flow state of the vessel or the size of thevessel. The transmitted blood pressure may be additive to the inherentradial outward force utilized to expand a significant length of thefunnel tip against the wall as the transmitted blood pressureessentially presses the impervious portion of the tubular mesh braidagainst the vessel wall. This added pressure can be summarized by theformula:

Occlusion efficiency of current occlusion device=radial force ofbraid*area of contact+nominal transmitted blood pressure*area of contact

Hence, the sealing ability of the current occlusion device 100 a can bea reflection of a combination of the radial force of the braid, thelength of the impervious wall contact portion, and the transmitted bloodpressure. It can be important to recognize that the coating or membranefree or open portion of the tubular mesh braid 200 should be sized sothat a portion of the coated or membrane comprising the imperviousportion of the tubular mesh braid 200 is not compromised and that thelength of contact of this portion to the wall is maximized while alsoproviding a distinct segment of the tubular mesh braid 200 that allowsingress and egress of fluid or blood. Experiments have demonstrated thatthe optimal length of the open or membrane devoid portion is between30-40% of the entire length of the tubular mesh braid 200 to accommodatea wide range of vessel sizes, although the ranges could vary between20-60% and even 3-80% for different or specific situations. Actualoverall braid length optimally for 2-6 mm vessels may be 1.6 cm with thecoated or membrane containing section comprising 1.1 cm and the membraneor coating devoid portion comprising 0.5 cm. In larger vessels, themeasurement may increase, but the approximate ratios will remain. Thisoptimized length provides proper buckling of the braid 200 to form afunnel, proper ingress and egress of fluid so that the funnel tipexpands and contracts easily, promptly, and without difficulty and alsoprovides enough length of contact with the vessel wall so that thedevice occludes flow in any situation.

Because of the addition of these important features of providing anoptimized section of the braid which does not comprise a membrane orcoating to the prior art, the current devices can function consistentlyto arrest blood flow in blood vessels no matter the blood vessel size,the systolic blood pressure or the flow state of the vessel. As thesystolic blood pressure is elevated, a corresponding pressure increasecan be transmitted to the inside of the elastomeric coated braid throughthis section of uncoated braid to press it against the arterial wallinsuring a proper seal and occlusion over varying blood pressures.

Experiments have demonstrated that the present occlusion device 100 acan provide a nominal radial force against the blood vessel wall whichis significantly augmented by the contribution of the patient's ownblood pressure which is transmitted through the specific section of thebraid 200 which is devoid of a membrane or coating. A 1.6 cm tubularmesh braid was constructed with 0.005″ diameter Nitinol wire and bondedto inner and outer tubular catheters and a silicone elastomer wasapplied over 1.1 cm of length maintaining a 0.5 cm length devoid of theelastomer. This arrangement caused the braid to buckle properly and forma funnel shape when the inner and outer catheter members were translatedrelative to one another. Compressive unloading measurements, which arereflective of the outward radial force of the device, were performed andthe results are presented in the table shown by FIG. 10.

The FIG. 10 graph demonstrates that the current occlusion device 100 a,as constructed, may exert only a very nominal pressure against thevessel wall which is insufficient to damage the intima or media of theblood vessel. To create an occlusion of the vessel, however, the forceexerted against the wall location 212 should be greater than thesystolic blood pressure or there may be an incomplete seal and leakageof blood around the device. The current device 100 a, because of thecombination of structural features, can achieve an outward radial forcegreater than the patient's systolic blood pressure by providing aminimal amount of inherent outward radial force insufficient to damagethe vessel wall added to the patient's transmitted systolic bloodpressure and it can do so relatively independently of the diameter of ablood vessel, as demonstrated in the graph. Hence, over a range ofsizes, a consistent and balanced limited inherent outward radialpressure can be achieved.

Calculations reveal that a systolic blood pressure of 150 mm Hg woulddemand at least 285 grams of outward radial pressure from a balloon oreven the prior art funnel catheter to occlude a blood vessel. At thislevel, a segment of the arterial wall adjacent to the upstream balloonface may experience 570 grams of force as there would be at least 285grams of outward radial force provided by the balloon and 285 grams fromthe 150 mm Hg blood pressure. This may be enough to damage the vesselwall and create immediate or delayed complications. The occlusiondevices of the present disclosure may subject the vessel wall to only285 grams from the transmitted blood pressure (which it is adapted towithstand) and 1.4 grams from the inherent outward radial force of thedevices. Hence, the occlusion devices of the present disclosure may addonly 0.5% added pressure to the wall over the transmitted blood pressurewhereas a balloon or even the prior art funnel catheter needs 100% addedpressure to occlude. Hence, the occlusion devices of the presentdisclosure may be dramatic improvements in safety over prior art devicesas vessel occlusion can be accomplished over a wide range of vesselsizes, flow rates and blood pressures by exerting a very minimal outwardradial pressure on the vessel wall which is insufficient to damage tothe vessel wall.

By providing a membrane devoid section of braid 200 through which theblood may flow into the space between the inner shaft 196 of the device100 a and the membrane containing braid 200, the total force of thedevice will generally always exceed the patient's systolic bloodpressure. The systolic blood pressure will often be exceeded by theinherent outward radial force of the braid 200 (which is less than onegram in many instances) as the outward radial force of the braid 200 andthe transmitted systolic blood pressure will often combine to press themembrane containing segment of the braid against the vessel wallpreventing any leakage of blood around the device 100 a.

To create a section of tubular braid 200 with portions that areimpervious to flow and other portions in which fluid and blood may flowfreely though, there may be several different methods available. Dipcoating is one very practical method to apply the elastomer to the braid200 and the braid 200 may be dipped into a solution of the elastomerjust enough to make part of the section of tubular braid 200 imperviousto fluids leaving the non-dipped portion free of the elastomer. Such dipcoating can be somewhat inexact and tedious however. It may beappropriate to dip the entire section of tubular mesh braid 200 into theelastomer or coat the entire section in some other manner and then lasercut the elastomer from the intended porous portion of the braid 200.This latter method can be more exact and precise and can leave a portionof the tubular braided section 200 with an elastomeric membrane orcoating and part of the section with no elastomer and freely porous.There are other means known in the art of creating porous and non-poroussections of tubular braid.

In some cases, it may be advantageous to provide another device topropel a blood clot or other substance into the mouth of a catheter oreven to expand to serve as a filter or an additional occlusion device.This may include a device to engage the blood clot and pull it towardthe catheter mouth or opening. Prior art traction devices includeballoon catheters, which are known to damage the vessel wall when fullyexpanded, and braided devices such as described in my prior U.S. Pat.No. 6,635,068, entitled “Occlusion, Anchoring, Tensioning and FlowDirection Apparatus and Methods for Use.” Even the latter prior arttraction device may damage the vessel wall in at least some cases by acombination of the outward radial force and the irregular surface causedby the braid. A prior art traction device 300 is illustrated in FIG. 11comprising a tubular outer sleeve 302 coaxially containing or over aninner member or shaft 303. An inner member 303 is attached to the distalend of the annular braid 304 at location 305. The outer sleeve 302 isattached to the annular braid 304 at location 306. FIG. 11 shows theconfiguration in which the device 300 is inserted into the blood vesselBV.

FIG. 12 demonstrates the configuration utilized for the functioning ofthe traction device 300, whether as a traction device on a thrombus orembolus, a filter device, or a tensioning device. The inner member 303may be moved relative to the outer sleeve 302 as indicated by the arrow307. This relative motion can cause the annular braid 304 to expandradially as shown at location 308. Typically, the inner shaft of thisdevice 300 is translated proximally relative to the outer shaft causingthe braid to expand in a more or less linear relationship to the degreeof translation. The materials and construction of the braid for thistraction device 300 may be chosen to increase the degree of outwardradial force to insure anchoring, tensioning, and occlusion and tomaximize the outward radial force.

As demonstrated in FIG. 13, the wall 310 of the blood vessel BV may beexpanded by the expansion of the wire basket 304 in this case as thebasket is secured to the wall. In fact, the object of the prior artdevice 300 is to provide enough outward radial pressure to the vesselwall 310 to firmly secure it to the vessel wall so that it may be usedas a tensioning device to advance other devices coaxially over it, toocclude the vessel and to anchor it firmly to the vessel wall. In theseinstances and for these applications, it may be advantageous to createan expansile element that exerts excessive outward radial force to thevessel wall to achieve the desired results in that particularapplication.

The vessel wall 310 may easily be damaged by the intended overexpansionor the inadvertent overexpansion of the braid, or other expansileelement, in a vessel. This damage is illustrated in FIG. 13 by the areaof hemorrhage or dissection 311 in the media of the blood vessel wall310. This damage may incite the exuberant reparative effort of the bloodvessel BV that results in restenosis. This damage caused by theuncontrolled expansion and distension of the blood vessel BV canstimulate a cascade of events in which smooth muscle cells and otherpluripotential cells migrate toward the lumen and create a scar of sortthat may occlude or severely narrow the vessel demanding furtherintervention at a later date. Addressing this dilemma is an object ofthe present disclosure.

The current inventor has conducted experiments have shown that damage tothe arterial wall can be avoided by such a device if constructed ofNitinol wires treated to provide a combination of stiffness andflexibility that not only creates a limited amount of outward radialforce against the wall, but also causes the braid to elongate whenplaced in smaller vessels. This limited radial force and elongation areillustrated by the present traction device 100 a in FIG. 14. When theinner member 303 is retracted relative to the outer sleeve 302, thebraid or other expansile element 304 expands to the vessel wall 310 butdoes not expand the wall 310. Instead, because of the combination ofstructural features, the braid or other expansile element 304 elongatesand does not distend or damage the vessel wall as in FIG. 13. There isno hemorrhage or dissection 311 with the elongation in FIG. 14 as thereis with the forceful radial expansion illustrated in FIG. 13. This lackof hemorrhage or dissection 311 may prevent the restenosis reaction fromoccurring. Generally, the traction device 300 a may not anchor or serveas a tensioning means as in the prior art device 300, but the device ofFIG. 14 may still function as a filter, clot traction device, oroccluder.

It is important that the improved current device provide a consistentand balanced outward radial force over a fairly wide range of vesseldiameters as well. In other words, the current device, because of acombination of structural elements, should provide a limited amount ofoutward radial force insufficient to damage the vessel wall which isindependent of the vessel wall diameter over a range of vesseldiameters.

While the current disclosure discusses the specific location of theelastomer and the elastomer free portion of the braid, there may incertain instances be a need for the elastomer to cover or be applied toonly a minimal section of the braid. This may especially be true whencomplete occlusion is not desirable. In these instances, the devices maybe constructed similarly to the above examples, with the elastomer freesection comprising a majority or even all of the braid. The elastomercontaining section may be small or absent in at least these cases. Theelastomer containing section may be placed on the braid so that aportion of the funnel is impermeable, but the funnel apparatus wouldtypically not obstruct or occlude flow.

The traction device 300 a of the present disclosure may utilize 0.004″diameter Nitinol wires that have been heat treated to provide acombination of stiffness and flexibility and by varying the pics perinch, the number of wires, the shape of the wires, the crossing angle ofthe wires as well as the density of any elastomeric coating, if any, sothat the expanded device will achieve a “programmed” outward radialforce even if attempts are made to expand the device beyond the diameterof the vessel. As the graph in FIG. 15 demonstrates, a braid sectionfully expanded to 5.5 mm in a 5.5 mm vessel can create about 12 grams ofoutward radial force or compressive unloading. It can essentially createthe same amount of outward radial force when expanded with the samedegree of translation of the inner shaft relative to the outer shaftover a range of different sized vessels because the braid sectionelongates rather than expands outward as a result of the propertiesinherent in the Nitinol wires and the braid pattern. The linearrelationship of the length of translation of the inner wire to the outersleeve with the degree and outward force of expansion present in priorart devices can be overcome in the present traction device by the use acombination of the flexibility of the Nitinol wires which is a result ofsize of wires and material choice, by heat treating, the pics per inch,the number of wires in the braid, the crossing angle of the braid, therelative stiffness of the silicone or other elastomer amongst otheritems. Particularly, heat treating the Nitinol wires in a jammed statewhere the braid is compressed into the smallest diameter and elongatedwill generally cause the braid to display a minimal amount of outwardradial force independent of the vessel size. Smaller and more flexiblewires will also tend to cause the device to elongate rather than expandoutward. Utilizing a small braid angle can be another importantstructural component to facilitate elongation vs. outward expansion andmay be as important as other structural features. With a larger braidangle, where one wire crosses another, that approaches 90 degrees, thebraid can resist collapsing and can maintain a relatively large amountof outward radial force. It can also resist elongation, which may bepart of the collapsing process. With smaller braid angles, the tubularbraid may not possess as much radial strength or outward radial force asthe braid wires can tend to move relative to each other to even smallerangles resulting in elongation of the tubular braid. This elongation canbe very important as it may prevent excessive outward radial force frombeing transmitted to the vessel wall and potentially damaging the wall.This improvement over the prior art traction devices (e.g., tractiondevice 300) utilizing a combination of the structural features above canprevent damage to the vessel wall by providing an effective way to pullclot or other substance into a catheter, whether a standard catheter ora braided funnel catheter described herein. It may also be utilized inother non-balloon expansile devices as mentioned above.

For example, if the prior art traction device 300 were placed in a 5.5mm diameter vessel and expanded to 5.5 mm so that it abuts the wall, itwould provide a certain amount of outward radial force against the wall.If the same device were utilized in a 3.5 mm vessel and expanded to 5.5mm diameter, the prior art traction device 300 may over-distend the wallof the vessel 2 mm or so to the 5.5 mm diameter creating a situationthat may very easily cause damage to the vessel wall as previouslyillustrated in FIG. 12 which may result in restenosis and other negativeevents. Overexpansion such as in this example may be common as the priorart traction devices can be so delicate that they cannot be easilyvisualized by fluoroscopy during a procedure, so the operator expandsthe braid by “feel” which is inexact at best. Instead of under expandingthe prior art traction device and being ineffective, the tendency may beto over expand it. An alternative to prevent this overexpansion andsubsequent damage to the vessel wall is to size the expansile device tothe size of the vessel and utilize a specifically sized device for eachvessel treated. For a 5.5 mm vessel, one may use a device sized toprovide a relatively low amount of outward radial force, and for a 3.5mm diameter vessel, one may use another device sized to provide arelatively low amount of outward radial force to the vessel wall of thatparticular size in that case. This custom sizing can be effective inlimiting the damage to the vessel wall, but can create stocking andinventory problems and may drive the cost of utilizing these devicesupward as a facility must stock multiple different sized devices tocover the range of vessel sizes from 2 mm or so in the cerebral,coronary, and below the knee arterial circulation to 8-10 mm in theiliac artery to 16 mm in the iliac veins and even larger in the inferiorvena cava and all sizes in between. Moreover, it may frequently benecessary to utilize the same type of device at different locationswithin the same patient, which may create the need for a catheter ordevice exchange which is time consuming and involves utilizing a newdevice for the second location which may cost thousands of dollars. Inessence, the use of specifically sized devices that avoid damage to thevessel wall may demand the costly and time consuming use of two or morespecifically sized devices in different vessels in the same patientrather than the serial use of one device which may safely and more timeefficiently treat a wide range of sizes. Hence, there is a real need tocontrol the outward radial pressure exerted on the vessel wall inexpansile devices to prevent vessel wall damage such as this tractiondevice, and also in embolic protection filters, occlusion devices, othertraction devices as well as most any expansile device by “programming”the expansile force into the device to create as little outward radialforce as possible over a wide range of diameters.

An elastomer may be provided to cover all or part of the braid 304,especially if the present traction device 300 a is used as a vascularoccluder, and may increase or decrease the outward radial forcedepending on the properties, thickness and consistency of the elastomer.A braid 304 of different programmed properties may be utilized in thatinstance.

Yet another way of controlling the outward radial force may be toutilize an elastic or elastomeric material, such as, but not limited to,silicone, urethane, neoprene, isoprene, Pebex, chronoprene and the likefor the inner member or outer sleeve, so that the inner member stretchesor the outer member compresses if attempts are made to over expand thedevice within a vessel. Instead of the excessive outward radial forcebeing transmitted to the wall, in this case, it can be transmitted tothe at least somewhat elastic inner member by stretching said memberafter a selected outward radial pressure is achieved by the braid orexpansile component or by compressing the outer sleeve after a selectedoutward radial pressure is achieved by the braid or expansile component,or by utilizing both. As well, ways to elongate the braid may also beutilized with either ways to stretch the inner member and with ways tocompress the outer sleeve, or both, to prevent outward radial force frombeing transmitted to the vessel wall beyond a selected level.

Furthermore, since the outward radial force is usually created in alinear relationship by pulling the inner member in relation to the outersleeve, a spring in the handle of the device attached to the innermember may prevent the full expansion of the braid and limit the outwardradial pressure. Hence, a spring may be used alone or in combinationwith any or all of the features listed above to limit the outward radialpressure.

Yet another way of providing minimal outward radial force to the vesselwall 310 with an expandable braid device 304, as illustrated in FIG. 16,is to provide an impermeable or partially impermeable elastomer ormembrane 315 on at least the distal section of the braid 304 and anelastomer or membrane free section 316 proximally so that the patient'sblood pressure may be transmitted beneath the impermeable or partiallyimpermeable aspect of the braid 315 as shown by arrows 317. Thetransmitted blood pressure may enhance the expansion of the expandablebasket 304 against the vessel wall 310. Hence, as in the apparatus 300 billustrated in FIG. 16, most of the outward radial force of theexpandable basket 304 to the wall of the blood vessel 310 may be fromthe patient's own blood pressure and not from the inherent outwardradial force of the expandable braid 304. In essence, the membrane orelastomer 315 may preferably be combined with either one or more of thepreviously discussed structural features of the braid to accomplish thisversion. This combination of structural features including the featuresthat cause the braid to lengthen rather than expand and the membrane 315may minimize the chance of damage to the blood vessel 310 by excessiveoutward radial force as is present in prior art devices.

Referring back to FIGS. 3 and 4, a dilator or obturator 220 may be usedin conjunction with the funnel catheter or occlusion device 100 a. Sincein the contracted configuration, the braid 200 is on the outside of theinner sleeve 196 and exposed to the vessel wall 210, there can be thepotential for the braid 200 to engage the vessel wall 210 and damage theintima as the braid 200 may not be as smooth as a usual smooth catheterexterior. The leading edge of the braid 200 at the tip of the cathetermay particularly have a lower smoothness. Hence, it may be advantageousto provide a way to create a smoother leading edge of the catheter.Usually, an obturator or inner catheter 220 can be utilized coaxiallywithin the catheter and over the guide wire to provide a more or lesssmooth transition from the guide wire (0.014″ to 0.035″) to the cathetershaft (0.044″ to 0.069″). In standard catheters, this configuration ofguide wire, obturator or inner catheter 220, and then the catheter maybe adequate but with the leading edge of the current catheter comprisinga section of braid and two wall thicknesses because of the inner andouter sleeves, there still may be some exposed braid over the obturatoror inner catheter which may engage the vessel wall. To create a smoothtransition and protect the wall from damage or an abrasion of the intimaby the exposed braid, the obturator or dilator 220 may be adapted asshown in FIG. 4 to fill the 0.006″-0.010″ difference between the OD ofthe contracted funnel catheter and then OD of the obturator or innercatheter.

FIG. 5 shows that the dilator or obturator 220 may be sized so that itfits within the inner diameter of the funnel catheters 100 and 100 apreviously described, but with an oversized tip or distal end thatextends beyond the distal end of the funnel catheter when the funnelcatheter is in a contracted or tubular configuration. Since the distaltip 221 of the dilator 220 should be just as large as the outer diameter(OD) of the funnel catheter 100, 100 a and oversized relative to theinner diameter (ID) of the funnel catheter 100, 100 a, it should becompressible to insert it through the hub end of the funnel catheter100, 100 a and to remove it from the funnel catheter 100, 100 a once thefunnel catheter 100, 100 a is in place at a target location in thevasculature. To accomplish this, the dilator 220 can have novel featuresthat can provide for protection against injury to the arterial wall bythe braided section and allow the oversized tip 221 to be inserted andwithdrawn through the funnel catheter even though the ID of the funnelcatheter is smaller than the OD of the tip of the dilator.

The shaft 222 of the dilator 220 may be sized to fit within the ID ofthe funnel catheter inner sleeve 196. The tip 221 of the dilator 220 maybe the same size as the OD of the funnel catheter 100, 100 a. Thedilator 220 comprises a lumen 223 for receiving a guide wire. So thatthe tip of the dilator 220 may fit through the ID of the funnel catheter100, 100 a, it must be compressible. One way of providingcompressibility may be to utilize a softer durometer substance withinthe tip. Another way may be to place a notch or a wedge shaped cutout230 in the tip as demonstrated in FIG. 6 which is a cross section ofFIG. 5 at a location A. Still another way may be to enlarge the guidewire lumen 223 to accommodate the compression needed for the larger tipto fit into the smaller lumen or to connect the guide wire lumen 223 tothe notch 230 as demonstrated in FIG. 7. Utilizing one or more of theseways can allow the larger tip 221 to compress so that it may be insertedand removed through the smaller catheter lumen. Placing the obturatordevice 220 through the hub or proximal end of the catheter 100, 100 ashould not be problematic as means to compress the tip 221 outside thebody are readily available and may comprise just ones finger and thumbor a special tool to receive the dilator tip and compress it to asmaller size by advancing it into a rigid funnel like structure. Whenplaced through the catheter lumen as demonstrated in FIG. 8, theoversized tip 221 of the dilator 220 may cover the leading edge of thefunnel catheter tip 206 and prevent any injury to the vessel wall thatmay be cause by the exposed braid otherwise. By angling the lumen 223toward the notch 230 at the end of the dilator 220, the guide wire canbe subtlety directed over that notch 230 and toward the wall of thevessel that one does not want the gap to encounter, hence “protecting”the gap or partially covering it and directing that portion of the tipaway from the vessel wall. Removing the oversized tip can be facilitatedby deploying the funnel apparatus of the funnel catheter as illustratedin FIG. 9 initially and then retracting the oversized, but compressible,dilator tip into the catheter shaft. While the primary objective of theoversized tip of the dilator 220 may be to protect the vessel wall fromthe catheter tip, the oversized tip 221 may also be utilized to retractthrombus or other material into the catheter. If utilized in a standardcatheter, for example, the oversized but compressible dilator tip 221and dilator 220 may be removed by simply retracting it into and out ofthe catheter shaft.

While preferred embodiments of the present invention have been shown anddescribed herein, it will be obvious to those skilled in the art thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to the embodiments of the invention describedherein may be employed in practicing the invention. It is intended thatthe following claims define the scope of the invention and that methodsand structures within the scope of these claims and their equivalents becovered thereby.

1. (canceled)
 2. A method of treating a bodily vessel, the methodcomprising: introducing a catheter toward a target site in the bodilyvessel; advancing a traction apparatus having an inner shaft, a tubularouter sleeve and an expandable mesh braid, from within an inner lumen ofthe catheter; expanding the expandable mesh braid within the targetsite; and retracting the expanded mesh braid to capture and retractmaterial in the target site into the inner lumen of the catheter,wherein the expandable mesh braid applies a predetermined amount ofradially outward force and elongates to minimize distending or damagingthe bodily vessel when the expandable mesh braid is expanded in thebodily vessel.
 3. The method of claim 2, wherein the bodily vesselcomprises a blood vessel.
 4. The method of claim 3, wherein the capturedand retracted material comprises a blood clot or a thrombus.
 5. Themethod of claim 2, wherein expanding the expandable mesh braid comprisesexpanding to appose an outer surface of the expandable mesh braidagainst an inner wall of the bodily vessel.
 6. The method of claim 5,wherein the expandable mesh braid comprises a plurality of wiresconfigured to exert the predetermined amount of radially outward forcewhen the expandable mesh braid is expanded in the bodily vessel.
 7. Themethod of claim 6, wherein the plurality of wires is configured to exertthe predetermined amount of radially outward force independently of aninner diameter of the bodily vessel.
 8. The method of claim 2, whereinexpanding the expandable mesh braid comprises expanding the expandablemesh braid to a predetermined outer diameter.
 9. The method of claim 2,wherein the expandable mesh braid has a shape memory characteristic. 10.The method of claim 2, wherein expanding the expandable mesh braidcomprises translating the inner shaft and the tubular outer sleeve ofthe traction apparatus relative to one another.
 11. The method of claim10, wherein a degree of a translation of the inner shaft and the tubularouter sleeve relative to one another has a non-linear relationship withan outer diameter of the expandable mesh braid.
 12. The method of claim10, wherein a degree of a translation of the inner shaft and the tubularouter sleeve relative to one another has a non-linear relationship witha radially outward pressure exerted by the expandable mesh braid. 13.The method of claim 2, wherein the expandable mesh braid has animpermeable or partially impermeable elastomer or membrane on at least adistal section of the expandable mesh braid.
 14. The method of claim 13,wherein expanding the expandable mesh braid comprises transmitting bloodpressure beneath the impermeable or partially impermeable elastomer ormembrane to expand and elongate the expandable mesh braid.
 15. Atraction apparatus for treating a bodily vessel, the traction apparatuscomprising: an inner shaft having a distal end; a tubular outer sleevecoaxially disposed over the inner shaft and having a distal end; and anexpandable mesh braid coaxially disposed over the inner shaft andcoupled to the distal end of the inner shaft and the distal end of thetubular outer sleeve, wherein the inner shaft and the tubular outersleeve are translatable relative to one another to shift the expandablemesh braid between contracted and expanded configurations, and whereinthe expandable mesh braid is configured to apply a predetermined amountof radially outward force and to elongate to minimize distending ordamaging the bodily vessel when the expandable mesh braid is expanded inthe bodily vessel.
 16. The traction apparatus of claim 15, wherein theexpandable mesh braid comprises a plurality of wires.
 17. The tractionapparatus of claim 16, wherein the plurality of wires is configured toprovide a combination of stiffness and flexibility.
 18. The tractionapparatus of claim 16, wherein the plurality of wires comprises aplurality of Nitinol wires.
 19. The traction apparatus of claim 16,wherein the plurality of wires is configured to exert the predeterminedamount of radially outward force independently of the inner diameter ofthe bodily vessel.
 20. The traction apparatus of claim 15, wherein theexpandable mesh braid in the expanded configuration is configured toexpand to appose an inner wall of the bodily vessel while minimizingresultant expansion of the bodily vessel.
 21. The traction apparatus ofclaim 15, wherein the expandable mesh braid is expandable to apredetermined outer diameter to apply the predetermined amount ofradially outward force.
 22. The traction apparatus of claim 15, whereinthe expandable mesh braid has a shape memory characteristic.
 23. Thetraction apparatus of claim 15, wherein a degree of a translation of theinner shaft and the tubular outer sleeve relative to one another has anon-linear relationship with an outer diameter of the expandable meshbraid.
 24. The traction apparatus of claim 15, wherein a degree of atranslation of the inner shaft and the tubular outer sleeve relative toone another has a non-linear relationship with a radially outwardpressure exerted by the expandable mesh braid.
 25. The tractionapparatus of claim 15, wherein the expandable mesh braid has animpermeable or partially permeable elastomer or membrane on at least adistal section of the expandable mesh braid and a permeable portion. 26.The traction apparatus of claim 25, wherein the permeable portion isconfigured to transmit blood pressure beneath the impermeable orpartially impermeable elastomer or membrane to expand and elongate theexpandable mesh braid.
 27. The traction apparatus of claim 15, whereinthe bodily vessel comprises a blood vessel.
 28. The traction apparatusof claim 15, wherein the inner shaft comprises a spring.